JP2006138295A - Fuel supply device for bifuel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply device for a bifuel engine for suppressing the production of vapor in liquid fuel being not used for operation. <P>SOLUTION: Individual fuel supply systems 30, 40 are provided for selectively injection-supplying CNG or gasoline to the engine 10. The fuel supply systems 30, 40 each have a fuel injection mechanism for injection-supplying fuel to the engine 20. As monitoring means for monitoring the temperature of the gasoline or its equivalent value, a temperature sensor 44a and a pressure sensor 44b are arranged in the fuel injection mechanism for the gasoline. In this construction, during operation in use of the CNG, when the temperature of the gasoline or its equivalent value satisfies predetermined conditions of accelerating the evaporation of the gasoline, change-over control is performed to the operation in use of the gasoline. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes an individual fuel supply system for selectively supplying the first and second different fuels to the engine, and a fuel injection mechanism for each of these fuel supply systems to inject and supply fuel to the engine. The present invention relates to a fuel supply device for a bi-fuel engine.

  In recent years, so-called bi-fuel engines have been proposed that can selectively use fuel from two types of fuel and supply it to the engine. For example, in such a bi-fuel engine, in an individual fuel supply system for each fuel, fuel stored in a fuel tank is pumped by a fuel pump to a delivery pipe that constitutes a fuel injection mechanism together with an injector. The pumped fuel is injected and supplied to an intake passage of the engine through an injector.

  By the way, the fuel injection mechanism is normally disposed in the vicinity of the combustion chamber of the engine for the purpose of injecting and supplying fuel to the engine, so that the temperature of the fuel injection mechanism is likely to rise due to radiant heat from the engine. Accordingly, when at least one of the fuels is liquid fuel and the liquid fuel is not used for operation and remains in the fuel injection mechanism, the temperature rise of the liquid fuel is promoted. Vaporized fuel (hereinafter referred to as vapor) may be generated. When the used fuel is switched in a state where the vapor is generated, the fuel including the vapor is injected from the injector of the corresponding fuel injection mechanism. That is, gas-phase fuel is originally injected from an injector provided to inject fuel in the liquid phase, and a desired fuel injection amount cannot be secured. As a result, the air-fuel ratio of the engine shifts to an unintended lean (lean combustion) side, and the operability as an internal combustion engine is impaired.

  Therefore, in order to solve such a problem, for example, a fuel supply device for an internal combustion engine described in Patent Document 1 has been proposed. This comprises a separate fuel supply system for selectively injecting and supplying first and second different fuels to the internal combustion engine, and each of these fuel supply systems injects and supplies fuel to the internal combustion engine And a fuel circulation mechanism for circulating the fuel in the fuel tank in the liquid phase via the fuel injection mechanism. Under such a configuration, during operation of the internal combustion engine using one of the first and second fuels, the temperature in the fuel injection mechanism of the other fuel or its equivalent value is monitored, and the monitored temperature Alternatively, when the equivalent value satisfies a predetermined condition that promotes vaporization of the fuel, the fuel circulation mechanism of the other fuel is activated, and the other fuel passes through the fuel supply system between the fuel tank and the fuel injection mechanism. To be circulated.

  Further, as a fuel injection system for an engine using liquid fuel and gaseous fuel, for example, a fuel injection system described in Patent Document 2 has been proposed. This consists of two systems: a liquid injector that injects fuel stored in a liquid phase in a fuel tank into the engine and an air injector that injects fuel stored in a gas phase in the fuel tank into the engine. I have. Under such a configuration, the amount of vapor generated in the fuel path from the fuel tank to the liquid injector is calculated based on the fuel temperature, the fuel pressure, etc., and each fuel generated by the liquid injector and the gas injector is based on the amount of vapor generated. The injection amount is metered to maintain the metering accuracy of the fuel injection amount high.

JP 2004-36458 A JP 2001-164997 A

  However, in the fuel supply device for an internal combustion engine described in Patent Document 1, the generation of vapor in liquid fuel that is not used for operation can be suppressed, but it is necessary to have a special fuel circulation mechanism. Therefore, it is desired to have a simpler configuration.

  Further, in the fuel injection system described in Patent Document 2, although a desired fuel injection amount is ensured, generation of vapor cannot be suppressed.

  Therefore, an object of the present invention is to provide a fuel supply device for a bi-fuel engine that solves the above-described problems and can suppress the occurrence of vapor in liquid fuel that is not used for operation.

  A fuel supply device for a bi-fuel engine according to a first embodiment of the present invention that solves the above-described problem includes separate fuel supply systems for selectively supplying first and second different fuels to the engine, and A fuel supply device for a bi-fuel engine having a fuel injection mechanism for injecting and supplying fuel to the engine by each fuel supply system, and during operation using the first fuel, the temperature of the second fuel or an equivalent value thereof And a switching control means for switching to the operation using the second fuel when the temperature of the second fuel or the equivalent value satisfies a predetermined condition for promoting the vaporization of the second fuel. To do.

  Further, a fuel supply device for a bi-fuel engine according to the second embodiment of the present invention that solves the above-described problem includes an individual fuel supply system for selectively supplying the first and second different fuels to the engine, A fuel supply device for a bi-fuel engine having a fuel injection mechanism for injecting and supplying fuel to the engine by each of these fuel supply systems, and during operation using the first fuel, the temperature of the second fuel or its Combustion temperature reduction control means for monitoring the equivalent value and controlling the temperature of the second fuel to lower the combustion temperature of the first fuel when the temperature of the second fuel or the equivalent value satisfies a predetermined condition for promoting vaporization of the second fuel. It is characterized by that.

  Here, the combustion temperature lowering control means is preferably at least one of a means for reducing the intake air amount, a means for reducing the fuel injection amount, or a means for retarding the ignition timing.

  In addition, a fuel supply device for a bi-fuel engine according to a third embodiment of the present invention that solves the above-described problems includes an individual fuel supply system for selectively supplying the first and second different fuels to the engine. A fuel supply device for a bi-fuel engine having a fuel injection mechanism for injecting and supplying fuel to the engine by each of these fuel supply systems, using the first fuel from the operation using the second fuel When the operation is switched to the above-described operation, there is provided a pressure increase control means for controlling the pressure of the second fuel of the fuel injection mechanism to increase to a predetermined pressure or higher.

  Here, it is preferable that the first fuel is CNG and the second fuel is gasoline.

  According to the first aspect of the present invention, during operation using the first fuel, when the second fuel that is liquid fuel that is not used for operation satisfies a predetermined condition for promoting vaporization, the second fuel Will be used for driving. As a result, since the second fuel with high possibility of vaporization in the fuel injection mechanism is consumed, it is possible to suppress the occurrence of vapor in the second fuel that is liquid fuel.

  Further, according to the second aspect of the present invention, during operation using the first fuel, when the second fuel that is liquid fuel that is not used for operation satisfies a predetermined condition for promoting vaporization, the operation is performed. The combustion temperature due to the first fuel being used is lowered. As a result, the radiant heat from the engine is reduced, and the temperature rise of the second fuel in the fuel injection mechanism is less likely to occur, so that the generation of vapor in the second fuel can be suppressed.

  Here, according to the form in which the combustion temperature lowering control means is at least one of a means for reducing the intake air amount, a means for reducing the fuel injection amount, or a means for retarding the ignition timing, combustion by the first fuel is performed. It is not necessary to provide a special mechanism for lowering the temperature.

  Further, according to the third aspect of the present invention, when the operation using the second fuel is switched to the operation using the first fuel, the second fuel is retained in the fuel injection mechanism. The pressure is increased to a predetermined pressure or higher and maintained. As a result, the saturation temperature of the second fuel that is not used for operation rises, so that vapor generation in the second fuel can be suppressed.

  Furthermore, according to the embodiment in which the first fuel is CNG (Compressed Natural Gas) and the second fuel is gasoline, the occurrence of vapor in the gasoline during operation using CNG is suppressed.

Below, this invention is demonstrated based on suitable embodiment.
First, a first embodiment of a fuel supply device for a bi-fuel engine according to the present invention will be described with reference to FIGS. 1 to 3.

  As shown in FIG. 1, the engine 10 has four cylinders. In order to operate the engine 10, air drawn from the intake port is introduced into the intake passage 22 via the air cleaner 21, and flows into the surge tank 24 while the flow rate is adjusted by the opening degree of the throttle valve 23. Then, the air flowing into the surge tank 24 is diverted to the intake manifold 25 that is branched and formed corresponding to each cylinder. The intake manifold 25 is provided with two fuel injection mechanisms. The fuel injected by these fuel injection mechanisms is mixed with the diverted air and sucked into each cylinder.

  Here, the engine 10 of the first embodiment is configured as a so-called bi-fuel engine in which a CNG fuel system 30 and a gasoline fuel system 40 are individually provided as fuel supply systems, and these fuels are selectively used. ing. That is, the intake manifold 25 is provided with a CNG injector 35 and a CNG delivery pipe 34 as a CNG fuel injection mechanism, and a gasoline injector 45 and a gasoline delivery pipe 44 as a gasoline fuel injection mechanism. Yes. Then, the fuel selectively injected and supplied from each of these fuel injection mechanisms is mixed with air in the intake manifold 25 and sucked into the combustion chamber 11 in which the spark plug 12 is disposed in the upper center.

  The fuel selectively injected and supplied in this manner is combusted in the combustion chambers 11 of the respective cylinders, and is discharged to the exhaust passage 52 through the exhaust manifolds 51 formed in a branched manner corresponding to the respective cylinders. A catalyst 53 that purifies the exhaust gas is disposed in the exhaust passage 52.

  Next, the CNG fuel system 30 as a fuel supply system will be described. The CNG fuel system 30 is a fuel supply that communicates the fuel tank 31 that stores CNG in a gas phase, the CNG delivery pipe 34, the CNG injector 35, the fuel tank 31, and the CNG delivery pipe 34. A regulator 33 disposed in the fuel supply line 32 for reducing the pressure of the high pressure CNG (hereinafter referred to as high pressure gas fuel) stored in the fuel tank 31 to the low pressure CNG (hereinafter referred to as low pressure gas fuel). And. A temperature sensor 32 a and a pressure sensor 32 b used for measuring the remaining amount of CNG in the fuel tank 31 are arranged in the fuel supply line 32 downstream of the fuel tank 31 and upstream of the regulator 33. In addition, the CNG delivery pipe 34 is provided with a temperature sensor 34a and a pressure sensor 34b used for measuring the fuel temperature and fuel injection pressure of the fuel injected from the CNG injector 35.

  Note that the high-pressure gas fuel filled in the fuel tank 31 at a filling pressure (for example, 20 MPa) is decompressed to a certain high control pressure (for example, 5 MPa) by the regulator 33 to become a low-pressure gas fuel.

  On the other hand, a gasoline fuel system 40 as a fuel supply system is inserted into a fuel tank 41 for storing gasoline in a liquid phase state, the gasoline delivery pipe 44, the gasoline injector 45, and the fuel tank 41. The fuel supply line 42 that connects the fuel tank 41 and the gasoline delivery pipe 44 and the feed pump 43 that pumps the gasoline stored in the fuel tank 41 to the gasoline delivery pipe 44 are configured. . In the fuel tank 41, a flow sensor 41a used for measuring the remaining amount of gasoline is arranged. Further, the gasoline delivery pipe 44 is provided with a temperature sensor 44a and a pressure sensor 44b used for measuring the fuel temperature and fuel injection pressure of the fuel injected from the gasoline injector 45.

  Since gasoline is a liquid, generally, when the gasoline injector 45 and the combustion chamber 11 are separated from each other, the gasoline injected from the gasoline injector 45 may adhere to the wall surface in the intake manifold 25. . However, if it adheres, gasoline cannot reach the combustion chamber 11 and it becomes difficult to execute a predetermined fuel injection amount. Therefore, in the first embodiment, the gasoline injector 45 is arranged in the vicinity of the engine 10, that is, in the vicinity of the intake port. As a result, the gasoline injector 45 is positioned downstream of the CNG injector 35. However, the present invention does not limit the positional relationship between the CNG injector 35 and the gasoline injector 45, and may be reversed, for example.

  The fuel supply device for a bi-fuel engine according to the present invention includes an electronic control unit (ECU) 100 that controls the injector 35 for CNG and the injector 45 for gasoline. The ECU 100 is composed of, for example, a microcomputer including a CPU, a memory for recording various programs and data, an input interface circuit, and an output interface circuit. The input interface circuit includes a throttle opening sensor 23a for detecting the throttle opening, temperature sensors 32a, 34a, 44a, pressure sensors 32b, 34b, 44b, a flow sensor 41a, a rotational speed sensor 101 for detecting the engine rotational speed, and A load sensor 102 for detecting the engine load is connected via electric wiring. The output interface circuit of the ECU 100 is connected to a step motor 23b or the like that allows the throttle valve 23 to be opened and closed, and the opening and closing of the ECU 100 can be controlled based on data obtained by the various sensors.

  An example of control of the fuel supply device for the bi-fuel engine having the above-described configuration will be described with reference to the flowchart of FIG. The control routine of FIG. 2 is a routine that is executed every predetermined time.

  First, when the control is started, it is determined in step S201 whether or not the operation using the CNG is performed in order to check whether or not the gasoline fuel is retained in the fuel injection mechanism such as the gasoline delivery pipe 44. When it is determined that the operation using CNG is being performed, the process proceeds to step S202, where it is determined whether or not vapor generation is predicted for the gasoline in the fuel injection mechanism. Specifically, it is determined whether or not the gasoline temperature or an equivalent value satisfies a predetermined condition for promoting the gasification of gasoline.

  Here, the conditions under which vapor generation in gasoline is predicted will be described. In general, as shown in FIG. 3, the vapor pressure line L1 (solid line in the figure) of gasoline is determined based on temperature and pressure, and the state of gasoline determined by temperature and pressure is lower than that of gasoline vapor pressure line L1. On the high temperature side, that is, the lower side in the figure, vapor is generated. In the first embodiment, a vapor generation prediction line L2 (dotted line in the figure) is defined on the high pressure and low temperature side of the gasoline vapor pressure line L1, and is stored in the memory as, for example, mapped data. Yes. Since the vapor generation prediction line L2 and the gasoline vapor pressure line L1 do not intersect, no vapor is generated when the gasoline is at a higher pressure and lower temperature than the vapor generation prediction line L2, that is, the upper side in the figure. Conversely, when the state of gasoline is lower than the vapor generation prediction line L2 and higher than the vapor generation prediction line L2, that is, the lower side in the figure, vapor is likely to be generated, and vapor generation is predicted. Therefore, in step S202, it is determined whether or not vapor generation is predicted for gasoline in the fuel injection mechanism by determining whether or not the gasoline state is lower than the vapor generation prediction line L2 in FIG. Is determined. Specifically, vapor generation occurs by searching the mapped data based on the temperature of the staying gasoline detected by the temperature sensor 44a and the pressure of the staying gasoline detected by the pressure sensor 44b. Whether or not is predicted.

  Next, when the occurrence of vapor is predicted, in step S203, it is determined whether or not the gasoline is larger than a predetermined amount in order to check whether or not the gasoline can be used for the operation of the engine 10. Specifically, the determination is made based on whether or not the remaining amount of gasoline in the fuel tank 41 detected by the flow sensor 41a is greater than a predetermined amount that is determined in advance through experiments. If it is determined that the gasoline is larger than the predetermined amount, the process proceeds to step S204, where the operation using CNG is switched to the operation using gasoline. As a result, gasoline that satisfies a predetermined condition for promoting vaporization in the fuel injection mechanism, that is, gasoline with high possibility of vaporization, is injected from the gasoline injector 45 and supplied to the combustion chamber 11 via the intake manifold 25. It will be used for driving.

  And by switching to the driving | operation using gasoline, gasoline with high possibility of vaporization is consumed, and the state of the gasoline in a fuel-injection mechanism changes to the state which vapor does not generate | occur | produce. Therefore, it is determined in step S205 whether or not vapor generation has been avoided. Specifically, the state of gasoline in the gasoline delivery pipe 44 obtained by the temperature sensor 44a and the pressure sensor 44b corresponds to a state of a predetermined region on the higher pressure and lower temperature side than the vapor generation prediction line L2 in FIG. It is determined whether or not to do so. As described above, in step S205, a criterion that is stricter than the vapor generation prediction line L2 is used as a criterion for determination. Therefore, the occurrence of vapor is reliably suppressed by satisfying the criterion.

  If it is determined in step S205 that the state of gasoline in the gasoline delivery pipe 44 does not correspond to the state of the predetermined region, it is determined that vapor generation has not been avoided, and the process returns to step S204. In this way, steps S204 and S205 are repeated until the occurrence of vapor can be reliably avoided. If it is determined that the generation of vapor has been avoided, the process proceeds to step S206, and the operation is switched to the operation using CNG.

  When it is determined in step S203 that the gasoline is not more than the predetermined amount, the process proceeds to step S207, and other means for avoiding the generation of vapor are executed. In addition, you may apply the means of this 2nd embodiment mentioned later or this 3rd embodiment as another means. Further, when the operation is not performed using CNG in step S201, or when the generation of vapor in the gasoline is not predicted in step S202, the routine is ended.

  As described above, according to the first embodiment, when the temperature or the like of gasoline that is liquid fuel that is not used for driving satisfies a predetermined condition that promotes vaporization of gasoline, this gasoline is used for driving. As a result, gasoline with high possibility of vaporization is consumed, and it is no longer present in the fuel injection mechanism, and vapor generation in the gasoline can be suppressed.

  Next, a second embodiment of the fuel supply device for a bi-fuel engine according to the present invention will be described. The hardware configuration in the second embodiment is the same as that of the first embodiment shown in FIG. Therefore, an example of a control routine of the fuel supply device for the bi-fuel engine in the second embodiment will be described with reference to FIG. However, step S401 and step S402 of the second embodiment correspond to step S201 and step S202 of the first embodiment, and thus description of these steps is omitted.

  If vapor generation is predicted during operation using CNG, in step S403, control is performed to reduce the intake air amount and fuel injection amount in order to lower the combustion temperature of the air-fuel mixture by CNG. Specifically, the throttle opening of the throttle valve 23 is controlled to be smaller than an appropriate value in order to reduce the intake air amount, or the fuel injection period from the CNG injector 35 is made shorter than the appropriate value in order to reduce the fuel injection amount. Control is performed. Specifically, the rotational speed sensor 101 and the load are adjusted so that the output exerted by the engine 10 when the engine 10 is operated at this appropriate value is suppressed to approximately 95%, that is, 5%. Based on the operation state detected by the sensor 102, the throttle opening and the fuel injection period are detected from the mapped data previously obtained by experiment and stored in the memory, and the engine 10 is operated with this detected value. The

  As a result, when the combustion temperature by CNG is lowered, the radiant heat from the engine 10 to the outside is also reduced, and the temperature rise of gasoline in the fuel injection mechanism is lowered and the temperature of the gasoline is lowered. It becomes.

  In this way, in order to examine whether or not the state of gasoline has changed to a state where no vapor is generated, it is determined whether or not vapor generation is avoided in step S404 as in step S205. In the second embodiment, when the vapor generation is not avoided even after the predetermined time has elapsed, the process proceeds to step S405, and the ignition timing by the spark plug 12 is retarded in order to avoid the vapor generation. Control is performed. Steps S404 and S405 are repeated until vapor generation is avoided. If it is determined in step S404 that the vapor generation is avoided, the process proceeds to step S406, and the intake air amount, the fuel injection amount, and the ignition timing are returned to appropriate values.

  As described above, according to the second embodiment, when the temperature of gasoline, which is liquid fuel that is not used for operation, satisfies the predetermined condition for promoting the vaporization, the control for reducing the combustion temperature by CNG is performed. Temperature rise of gasoline in the fuel injection mechanism due to radiant heat from the engine 10 is less likely to occur. As a result, the temperature or the like of the gasoline decreases, and it is possible to suppress the vapor from being generated in the gasoline retained in the fuel injection mechanism.

  However, in the above control, in order to lower the combustion temperature by CNG, the throttle valve 23 is throttled to reduce the intake air amount, or the CNG injector 35 is opened for a shorter period to reduce the fuel injection amount. Although the ignition timing is retarded, control for lowering the combustion temperature may be performed only by performing at least one of them. In addition, since such control is intentionally performed to reduce the output of the engine 10, it is preferable to perform control to immediately return to the original state when the gasoline state has changed to a state where vapor generation can be avoided. . Therefore, a reference approximate to the vapor generation prediction line L2 may be used in determining whether or not the vapor generation in step S404 has been avoided. Of course, it may be determined whether or not vapor generation has been avoided on the vapor generation prediction line L2.

  Next, a third embodiment of the fuel supply device for a bi-fuel engine according to the present invention will be described. The hardware configuration in the third embodiment is the same as that of the first embodiment shown in FIG. Therefore, an example of a control routine of the fuel supply device for the bi-fuel engine in the third embodiment will be described with reference to FIG.

  First, when control is started, it is determined in step S501 whether or not an operation using gasoline is being performed. When it is determined that the operation is using gasoline, the process proceeds to step S502, where it is determined whether or not there is an instruction to switch from the operation using gasoline to the operation using CNG. In the third embodiment, the fuel used for driving is automatically switched by searching the mapped data stored in the memory that has been obtained in advance through experiments based on the operating state of the engine 10. ing. Therefore, when it is determined from this search result that there has been an instruction to switch to operation using CNG, the process proceeds to step S503.

In step S503, it is determined whether or not CNG is greater than a predetermined amount in order to check whether or not operation using CNG is possible. Specifically, the determination is made based on whether or not the remaining amount of high-pressure gas fuel in the fuel tank 31 detected by the temperature sensor 32a and the pressure sensor 32b is greater than a predetermined amount. As a result, if it is determined that the amount of CNG is greater than the predetermined amount, the process proceeds to step S504, and the operation is switched to the operation using CNG. Simultaneously with this switching, the injection of gasoline from the gasoline injector 45 is stopped.
When the fuel is switched from gasoline to CNG, the set pressure of the feed pump 43 is changed to a higher pressure side than the predetermined pressure in step S505 in order to increase the pressure of the gasoline in the fuel injection mechanism, particularly the gasoline delivery pipe 44. Then, the feed pump 43 is operated. As a result, the gasoline in the fuel tank 41 is pumped to the gasoline delivery pipe 44 with this high pressure. As a result, the pressure of the gasoline in the gasoline delivery pipe 44 is increased.

  In step S506, whether or not the internal pressure of the gasoline delivery pipe 44 detected by the pressure sensor 44b is higher than the predetermined pressure in order to check whether the pressure of the fuel injection mechanism such as the gasoline delivery pipe 44 is equal to or higher than the predetermined value. Is determined. When it is determined that the pressure of the gasoline delivery pipe 44 is not higher than the predetermined pressure, it is determined that the pressure of the gasoline is insufficient, and the process returns to step S505 to repeat steps S505 and S506. This is performed until it is determined that the pressure of the gasoline delivery pipe 44 is higher than a predetermined pressure. When it is determined that the pressure of the gasoline delivery pipe 44 is higher than a predetermined value, the process proceeds to step S507 and the feed pump 43 is stopped.

  As described above, according to the third embodiment, when gasoline is retained in the fuel injection mechanism, the pressure is increased to a predetermined pressure or higher and maintained. As a result, since the saturation temperature of gasoline in the fuel injection mechanism increases, it is possible to suppress the occurrence of vapor in the gasoline.

  As mentioned above, although the fuel supply apparatus of the bi-fuel engine which concerns on this invention was demonstrated based on preferable embodiment, this invention is not limited to these embodiment, The combination of these embodiment is included. Moreover, in the said embodiment, although gasoline was used as liquid fuel and CNG was used as gaseous fuel, it may be other than these. Specifically, LPG can be used as the liquid fuel. It is also possible to use hydrogen gas, propane gas, or dimethyl ether gas as the gaseous fuel. Furthermore, when predicting the occurrence of vapor, the outside air temperature may be used.

It is a whole line figure showing an outline of a bi-fuel engine to which the present invention is applied. It is a flowchart which shows an example of the control routine of 1st embodiment in this invention. It is a graph which shows the vapor pressure line of gasoline with the vapor generation | occurrence | production prediction line of 1st embodiment. It is a flowchart which shows an example of the control routine of 2nd embodiment in this invention. It is a flowchart which shows an example of the control routine of 3rd embodiment in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Combustion chamber 12 Spark plug 21 Air cleaner 22 Intake passage 23 Throttle valve 23a Throttle opening sensor 24 Surge tank 25 Intake manifold 31 Fuel tank 32 Fuel supply line 32a Temperature sensor 32b Pressure sensor 33 Regulator 34 CNG delivery pipe 34a Temperature sensor 34b Pressure sensor 35 CNG injector 41 Fuel tank 41a Flow sensor 42 Fuel supply line 43 Feed pump 44 Gasoline delivery pipe 44a Temperature sensor 44b Pressure sensor 45 Gasoline injector 51 Exhaust manifold 52 Exhaust passage 53 Catalyst

Claims (5)

A bi-fuel having a separate fuel supply system for selectively supplying first and second different fuels to the engine, each of which has a fuel injection mechanism for injecting and supplying fuel to the engine An engine fuel supply device,
During operation using the first fuel, the temperature of the second fuel or an equivalent value thereof is monitored, and the temperature of the second fuel or the equivalent value satisfies a predetermined condition for promoting vaporization of the second fuel. A fuel supply device for a bi-fuel engine, comprising switching control means for switching to operation using the second fuel. A bi-fuel having a separate fuel supply system for selectively supplying first and second different fuels to the engine, each of which has a fuel injection mechanism for injecting and supplying fuel to the engine An engine fuel supply device,
During operation using the first fuel, the temperature of the second fuel or an equivalent value thereof is monitored, and the temperature of the second fuel or the equivalent value satisfies a predetermined condition for promoting vaporization of the second fuel. A fuel supply device for a bi-fuel engine, comprising: a combustion temperature lowering control means for controlling the combustion temperature of the first fuel to be lowered.   3. The buy according to claim 2, wherein the combustion temperature lowering control means is at least one of a means for reducing the intake air amount, a means for reducing the fuel injection amount, and a means for retarding the ignition timing. Fuel supply system for fuel engine. A bi-fuel having a separate fuel supply system for selectively supplying first and second different fuels to the engine, each of which has a fuel injection mechanism for injecting and supplying fuel to the engine An engine fuel supply device,
When the operation using the second fuel is switched to the operation using the first fuel, the pressure increase control for controlling the pressure of the second fuel of the fuel injection mechanism to be increased to a predetermined pressure or higher. A fuel supply device for a bi-fuel engine, characterized by comprising: The fuel supply device for a bi-fuel engine according to any one of claims 1 to 4, wherein the first fuel is CNG and the second fuel is gasoline.

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